Chair control

ABSTRACT

A chair control has a threaded element with a thread extending along an axis. A retainer limits axial freedom of the threaded element and a user control rotates the threaded element. A spring backstop is threaded to the threaded element and a spring with a projection has this projection stopped against the spring backstop.

BACKGROUND

This invention relates to a chair control and to a spring tensioner for a chair control.

A chair control may have a main frame, a seat bracket, and a back bracket. The main frame may be configured for mounting on a seat post and may support the seat bracket. A chair seat may be attached to the seat bracket and a chair back rest may be attached to the back bracket. The back bracket may be hinged to the seat bracket, and a main spring may act between the main frame and the back bracket in order to bias the back bracket toward a rest position. In a typical configuration, the main spring is a helical spring housed in a cylindrical, downwardly projecting, stub of the main frame. A hand wheel extends below the cylindrical stub. When a chair occupant leans back in the chair, the back bracket will pivot against the urging of the main spring so that the back rest tilts backwards. Rotation of the handwheel in one direction compresses the spring in order to increase the urging force applied by the spring. Thus, the occupant can set the force with which the main spring resists tilting of the backrest by turning the handwheel.

This invention seeks to provide an improved mechanism.

SUMMARY OF INVENTION

A chair control has a threaded element with a thread extending along an axis. A retainer limits axial freedom of the threaded element and a user control rotates the threaded element. A spring backstop is threaded to the threaded element and a spring with a projection has this projection stopped against the spring backstop.

In another aspect of the invention, a spring tensioner for a chair control mechanism has a hand crank, a worm gear rotated by the hand crank, a pinion and captive bolt rotated by the worm gear, a retainer limiting axial freedom of the bolt, and a spring backstop threaded to the bolt.

Other features and advantages of the invention will become apparent from the following description in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

In the figures which illustrate an example embodiment of the invention,

FIG. 1 is a top perspective view of a chair control made in accordance with this invention,

FIG. 2 is a top perspective view with the seat bracket removed,

FIG. 3 is a top perspective view with the seat bracket and back bracket removed,

FIG. 4 is an exploded view of a portion of the chair control,

FIG. 5 is a cross-sectional view along the lines V-V of FIG. 3,

FIG. 6 is a partially exploded view of a portion of the chair control,

FIG. 7 is a perspective view of a portion of the chair control,

FIG. 8 is top perspective view of a portion of the chair control, and

FIGS. 9A and 9B are side views of a portion of the chair control showing operation of this portion of the chair control.

DETAILED DESCRIPTION

Turning to FIGS. 1 and 2, a chair control 10 has a main frame 12, a seat bracket 14, and a back bracket 16. The seat bracket 14 may be mounted to the main frame by pins 18 and may have flanges 20 with bores 22 by way of which a chair seat may be affixed to the seat bracket.

The back bracket 16 may be pivotably joined to the main frame by shaft 26. A number of user controls may extend from the main frame, namely a spring tension hand crank 30, a gas control paddle 32, and a backrest tilt lock control 34. As is apparent, the paddle 32 may extend from a cylindrical sleeve 36 which is supported for rotation on an arm 38 extending from the hand crank. The hand crank itself may have a depending finger 40 terminating in a rotatable tip 42 which may be grasped by a user.

Turning to FIGS. 3 to 5, a main spring 50 may have two helically wound sections 46 a, 46 b which each terminate at an inner end in a projection: tangs 52 a and 52 b. The tangs project from one side of the helically wound sections. Each helically wound section may terminate at its opposite, outer, end in another projection: arms 48 a and 48 b, which are joined by a bar 54. The arms project from an opposite side of the helically wound sections.

The main spring 50 may be supported in main frame 12 by an annular shaft 56 which extends through the central axis of the helically wound sections of the spring. The annular shaft is carried on shaft 26 (FIG. 2) and the ends of shaft 26 extend through openings 58 in the main frame (and openings in the back bracket).

The bar 54 of the spring abuts the underneath of the back bracket 16 (FIG. 2). The two tangs 52 a, 52 b abut the underneath of a wear plate 62 associated with a threaded spring backstop 60. The spring backstop 60 is threaded to a bolt 66. The threaded shaft of the bolt passes through a retainer plate 70. Bolts 74 extend through the main frame 12, a block 76, and the retainer plate. Nuts 75 are screwed to the bolts 74 to fix the retainer plate 70 to the block 76, and to fix both the retainer plate and the block within the main frame. A thrust bearing 72 may be used to reduce friction between the head of the bolt 66 and the retainer plate 70 when the bolt 66 is turned. The thread of the shaft of bolt 66 may have about five turns per inch. This may be achieved by, for example, utilising a triple start thread that has sixteen turns per inch.

A cavity in block 76 is configured to house a pinion 78 and a worm gear 80 so that these gears are held in meshing relation. The pinion 78 may have a hexagonal central bore into which the hexagonal head of bolt 66 is received such that the pinion and bolt have a common central axis and the bolt is constrained to turn with the pinion. The shaft 38 extending from hand crank 30 is joined to the worm gear 80 such that turning the crank turns the worm gear. In this regard, the end of shaft 38 may be hexagonal and fit in a hexagonal opening in the end of the worm gear, as seen in FIG. 6.

Turning to FIG. 6 along with FIGS. 3 and 5, block 76 may have an extension 84 to which a gas control lever 86 is mounted by pivots 88. A control end 90 of the lever may abut a gas control finger 92 of a gas cylinder 94. A controlled end 96 of the lever may have a slot 98 which receives a boss 102 extending from the cylindrical sleeve 36 of the paddle 32.

Turning to FIGS. 7 and 8, a resilient arm 106 depends from the opposite side of block 76. The resilient arm 106 has lands 108, 110 on either side of a protuberance 112. The back rest tilt lock control 34 may be rotationally mounted to a shaft 114 which extends through an opening in main frame 12 and is joined to a cam finger 118. The cam finger may abut arm 106 and deflect it from its rest position. The cam finger may have a cylindrical receptor 120 which receives a boss (not shown) extending from the back rest tilt lock control 34 through a slot 122 in the main frame. The cam finger may also have a projection 124 with a bore through which a stiff wire 126 extends. Springs 128, 130 may extend over the stiff wire 126 on either side of the projection. Each spring may be sandwiched between the projection and a respective enlargement 132, 134 (FIG. 9A) on the stiff wire.

An dog 136 may be pivotably joined to a plate 138 proximate one side of the plate 138. Wire 126 may be joined via the dog 136 to the plate 138. The plate may be pivoted to the main frame, proximate the other side of the plate, by a pivot 140. A locking tongue 142 may extend from plate 138 and be received within one of an array of locking receptors in a rack (not shown) extending from the back bracket 16 (FIG. 3). As seen in FIGS. 9A and 9B, the cam finger 118 has two stable positions, one on either side of the protuberance 112.

In operation, a user may rotate hand crank 30 to turn worm gear 80. This, in turn, rotates pinion 78 and its captive bolt 66. The bolt is constrained from moving axially upwardly by retainer plate 70. Consequently, when the bolt is rotated in one direction, threaded spring backstop 60 is drawn toward the retainer plate. This moves the tangs 52 a, 52 b of the springs downwardly thereby increasing the pressure that the bar 54 of the spring exerts on back bracket 16. This increases the force with which the main spring 50 resists backward tilting of any backrest attached to the back bracket. Conversely, if the bolt is rotated in the opposite direction, the spring backstop 60 moves away from the retainer plate 70. This allows the tangs 52 a, 52 b of the spring to move upwardly thereby decreasing the pressure that the bar 54 of the spring exerts on back bracket 16 and reducing the resistance to backward tilting of the backrest. By providing a thread for bolt 66 that effectively has a low number of turns per inch (e.g., a triple start thread), the user may make a substantial adjustment in the spring tension with a relatively small adjustment to hand crank 30. This therefore makes adjustment of the spring tension quicker and less tiring for the user.

The user may lock the backrest at different tilt angles by rotating the backrest tilt lock control 34 so that cam finger 118 moves from an unlocking position shown in FIG. 9A, over protuberance 112, to a locking position shown in FIG. 9B. Resilient arm 106 deflects to allow this movement. In the locking position, spring 128 is compressed, thereby urging wire 126 in a locking direction L. This, through dog 136, urges the plate 138 to rotate in the locking direction. In consequence, if the locking tongue 142 is registered with one of the array of locking receptors in the rack (not shown) extending from the back bracket 16, the tongue will enter the registered receptor and the back bracket will be locked in position. If, however, the tongue is not registered with any receptor, then the tongue will simply be pushed against the rack and pop into a receptor whenever the angle of the back bracket changes so as to register any receptor with the tongue.

To unlock the backrest, the user may rotate the backrest tilt lock control 34 so that cam finger 118 moves back to the unlocking position shown in FIG. 9A. This compresses spring 130 which urges wire 126 in a direction opposite locking direction L. The pressure exerted by the main spring 50 may create a binding force between the tongue and the side of the receptor receiving the tongue. This may prevent the tongue from popping out of the receptor until a user may adjusts their weight in the chair to relieve this binding force.

The user may push paddle 32 in order to cause boss 102 extending from the sleeve 36 joined to the paddle to tilt the control end 90 of lever 86 against the gas control finger. By depressing the gas control finger in this way, the height of the chair may be adjusted.

From FIG. 1 it will be apparent that the three user controls 30, 32, 34 may project from the sides of the chair control 10. This has the advantage that a chair occupant never need reach between their legs to make a chair adjustment. Further, with the gas control paddle 32 having a sleeve 36 co-axially mounted to the arm 38 extending from the hand crank 30, these two controls may conveniently be placed in close proximity. For aesthetics, the chair control may be designed as shown in FIG. 1 with the chair back lock arm 34 co-axial with the hand crank arm 38.

Many modifications are possible. For example, pinion 78 and worm gear 80 could be replaced by two bevel gears. Also the spur and worm gears could be reversed so that the bolt 66 is captured by the worm gear. Indeed, if the thread of bolt 66 were provided with a sufficiently large pitch, in place of the gears and hand crank, a lever could be connected directly to the bolt extending at roughly a right angle to the bolt. In this instance, the lever could be rotated to directly rotate the bolt and move the spring backstop. With all of these options, the chair control retains the advantage that an occupant never need reach between their legs to make a chair adjustment. In another embodiment, it would be possible to omit the gears and have the hand crank connected directly to the end of the bolt so that the crank projects downwardly from the chair control. This is not preferred, however, as the chair control would lose its advantage of never requiring an occupant to reach between their legs to make a chair adjustment.

While in the illustrated embodiment, the head of the bolt 66 is captured by a hexagonal bore in the pinion, optionally, the bolt, or any threaded shaft, could be affixed to the pinion in any suitable fashion. In another embodiment, the bolt 66 could be replaced by a nut captured by, or affixed to, the pinion. In this case, the spring backstop could support a threaded shaft which extends downwardly into threaded engagement with the nut.

Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims. 

1. A chair control, comprising: a threaded element having a thread extending along an axis; a retainer for limiting axial freedom of said threaded element; a user control for rotating said threaded element; a spring backstop threaded to said threaded element; and a spring having at least one projection, said at least one projection stopped against said spring backstop.
 2. The chair control of claim 1 wherein said user control comprises a hand crank.
 3. The chair control of claim 2 further comprising: a first gear joined to said hand crank for rotation therewith; and a second gear meshing with said first gear, said second gear coupled to said threaded element for driving said threaded element to rotate.
 4. The chair control of claim 3 wherein an axis of rotation of said second gear is coincident with a central axis of said threaded element.
 5. The chair control of claim 4 wherein said thread effectively provides about five turns per inch.
 6. The chair control of claim 4 wherein said threaded element is a threaded shaft.
 7. The chair control of claim 4 wherein said threaded element is a bolt, a head of said bolt being coupled to said second gear.
 8. The chair control of claim 7 wherein said thread of said bolt is a triple start thread.
 9. The chair control of claim 7 wherein said head of said bolt has a multi-faced side and wherein said second gear has a corresponding multi-faced bore engaging said bolt head.
 10. The control of claim 6 further comprising a main frame and a backrest bracket, said spring acting between said spring backstop and said backrest bracket.
 11. The control of claim 10 wherein said retainer is a retaining member held to said main frame.
 12. The control of claim 11 wherein said first gear is a worm gear and said second gear is a pinion.
 13. The control of claim 12 further comprising: a gas control lever; and a user control arm co-axially mounted to said hand crank for rotation through an arc, one of said control arm and said lever having a boss and another of said paddle and said lever having a receptor for receiving said boss such that rotation of said paddle through said arc pivots said lever.
 14. The control of claim 3 further comprising a block supporting said first gear and said second gear, said retainer being joined to said block.
 15. The control of claim 14 wherein said block has a depending resilient arm having a land on either side of a protuberance.
 16. The control of claim 15 further comprising a cam finger supported for rotation, an end of said cam finger abutting said arm whereby said cam finger has two stable positions, one on each side of said protuberance.
 17. The control of claim 16 wherein said user control is a first user control, and further comprising a second user control for rotating said cam finger.
 18. The control of claim 17 further comprising a back rest lock operated between a lock position and an unlock position by rotation of said cam finger between each of said two stable positions.
 19. The control of claim 1 wherein said spring has at least one helically wound section and said projection extends from an end of said at least one helically wound section.
 20. The control of claim 19 wherein said spring has a second projection extending from an opposite end of said at least one helically wound section.
 21. The control of claim 20 wherein said control further comprises a back bracket and wherein said second projection abuts said back bracket.
 22. A spring tensioner for a chair control mechanism, comprising: a hand crank; a worm gear rotated by said hand crank; a pinion and captive bolt rotated by said worm gear; a retainer limiting axial freedom of said bolt. a spring backstop threaded to said bolt. 